Four Horns:Haven't done it, but try bringing an Ice weapon. Bring strong armour, lots of Potions, Mega Potions, etc. (Ancient Potion = Kelbi Horn + Immunizer). Sonic bombs are very important, bring as many as you can (I would bring Book of Combo's, 1, 2, 3 & 4 with 20 Gunpowder, 20 Screamers and 10 Sonic bombs). Throw them over where they dug underground after their tail is under, DO NOT throw them when they're on rage. I'd consider bringing a weapon that can block because it's not easy getting away from them. Also some strategies I use with something that blocks is: Block against a wall, and wait until he charges into you (if he has his horns still) he will get stuck in the wall, giving you more advantage to kill him.

Shogun's Encampment:I cleared that one with a lot of Potions and a couple of Mega Potions in no time. I used my Devil Slicer to bet them, and used 1 Shock Trap on one Shogun. But if you hate being hit, bring something that can block. Sorry but that's all I can give you for that one ><

ya i used the devil slicer but really any thunder weapon would do great ... khezu Gs, or the kirin Gs are good ones and hammers cream them pretty good ... I cannot past that four horns i alway get owned hope that helps guys

Shoguns Encampment really is quite easy, once you kill one the other will go down really quickly, i dunno why but tht always happens with me on duel quests. I used Devil slicer for it and kept on going for the shells until its two shells have gone then attack it as much as i can. For Four horns I used Blango Decimator and did it using 20 potion and around 10 mega potions. I went for the normal Diablos first just cos i thought that if i left him he would be a nouisance while trying to kill the Black Diablos. BEWARE they are together alot but youll just have to cope with it until you kill one cos if you dont youll probably run out of time. Also bring a whole lot of sonic bombs and gunpowder+screamer as sed earlier.